Bryan McAllister’s personal reference notebook
July 27, 2026Short & citedBlog
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Field Notes • Plant

Tree

A tree is a perennial woody plant with an elongated stem, or trunk, that supports branches and leaves.

Updated July 27, 20261 min readCited sources

A tree is a perennial woody plant with an elongated stem, or trunk, that supports branches and leaves. Trees play key ecological roles by storing carbon, moving water, and producing oxygen.

What it is

A tree is commonly defined in botany as a perennial woody plant with a single main trunk and a crown of branches and leaves. Most trees have roots for anchoring and uptake, a trunk for support and transport, and branches that carry leaves. Their woody tissues allow secondary growth, increasing in girth over time.

Why it matters

Trees contribute to ecosystems by storing carbon dioxide, stabilizing soils, cycling water, and providing habitat and food. Through photosynthesis, they convert carbon dioxide and water into sugars and release oxygen. In Canada, forests cover large areas supporting biodiversity, timber industries, and carbon storage.

Key details

Trees include many unrelated plant lineages sharing a similar growth form. They are grouped by leaf type, wood type, climate adaptation, and lifespan. Some trees exceed 110 metres in height, while others live for thousands of years.

In short

  • Trees are woody perennial plants with a main trunk.
  • Most trees have branches, leaves, and roots.
  • Trees produce oxygen through photosynthesis.
  • Some trees live for thousands of years.
Canadian angle

Trees are central to Canada’s forests, which cover large areas of the country and support biodiversity, timber industries, recreation, and carbon storage. Tree identification is also important in Canadian forestry, ecology, and urban planning.

Quick questions

What is a tree?
A tree is a perennial woody plant with an elongated stem, or trunk, that supports branches and leaves above the ground.
How tall can a tree grow?
Tree height varies by species, but some of the tallest recorded trees exceed 110 metres. Many trees are much shorter, growing only a few metres tall.
How do trees produce oxygen?
Trees produce oxygen during photosynthesis. Their leaves take in carbon dioxide and use sunlight and water to make sugars, releasing oxygen as a byproduct.

Sources

  1. Wikipedia — https://en.wikipedia.org/wiki/Tree
    Supports: General botanical definition of a tree as a perennial plant with an elongated stem or trunk supporting branches and leaves.
  2. Encyclopaedia Britannica — https://www.britannica.com/plant/tree
    Supports: Tree definition, woody perennial growth form, and ecological role including carbon storage and oxygen production.
  3. Montana State University Extension — https://www.montana.edu/extension/forestry/publications/fact-sheets/FF_What%20is%20a%20tree_PK.pdf
    Supports: Tree structure, typical height range, oldest known single-stem tree claim, tallest recorded tree claim, and photosynthesis oxygen byproduct.
  4. EcoTree — https://ecotree.green/en/blog/what-is-a-tree
    Supports: Tree definition, roots, and FAO-style height-based criteria used in some contexts.
  5. Utah State University Extension — https://extension.usu.edu/forestry/trees-cities-towns/tree-selection/what-is-a-tree
    Supports: Practical identification criteria for trees and distinction from shrubs.
  6. Dictionary.com — https://www.dictionary.com/browse/tree
    Supports: General definition and common human uses of trees, including oxygen production.